Magic Lantern for Canon 7D

I'm a wedding dj who has been getting into photography and videography as well. I recently bought a Canon 7d and have been doing video gig logs to help promote myself to future clients. I've been noticing that I can't control the auto level in the camera while I'm doing video. I did update the firmware to the 2.0 version but I still can't control the levels while recording...only prior to.

I've heard about magic lantern and I found a website which I will post below...

I'm wondering, is this a reliable website for magic lantern? Is magic lantern safe to put on my camera? Do I have to have a specific card in the camera to run magic lantern or does the firmware get loaded onto the camera itself? What are your thoughts on magic lantern?